The inventor of the present invention has previously disclosed the invention of a dihedral corner reflector array optical device, consisting of multiple pairs of approximately perpendicular specular planes, and being capable of image forming (see Patent Reference No. 1). The above optical device, when an object (including physical objects and images) is placed to one of its sides, will reflect the light emitted from the above object by the aforementioned pairs of specular surfaces (heretofore called ‘dihedral reflectors’) while passing the reflected light through it, thus forming a reversed real image of the above object at the other side of the above optical device. The above optical device thus realizes a new way of optical imaging.
The principle of operation of the above mentioned optical device is based on the reflection of light by specular surfaces; thus it solves a problem with a-focal lens arrays using refraction by micro-lenses, (see Patent Reference No. 2), which is the need of observation from an approximately perpendicular direction from the surface of the optical device; therefore the present invention has the benefit of being suitable for observation from acute angles from the surface of the optical device.    Patent Reference No. 1: WO 2007/116639    Patent Reference No. 2: JP 2005-010755